The production of logs is known to imply feeding a continuous web of paper along a predetermined path. At a given point of said path, a discontinuous transverse cut is operated on the web in order to subdivide it into sections or sheets of preset length which can be torn off.
This procedure comprises using tubular cardboard elements (commonly said “cores”) on the surface of which a preset amount of glue is spread to allow gluing the first sheet of the log to be formed. The procedure also provides for using winding rollers which drive into rotation the core on which the paper is wound. The log-forming process ends up when a preset amount of paper has been wound on the core. At this point, the formation of the next log begins. At the end of the formation process, it is necessary to glue the last sheet of each log on the underlying sheet to avoid the spontaneous unwinding of the same log. This type of gluing is defined as “edge closing”. When a number of preset sheets result wound up on the log in the course of formation, the paper web is cut off, that is, the last sheet of the log in the course of formation is separated from the first sheet of the next log to be formed.
Patents EP 524158, GB 210568 and EP 694020 disclose devices used to cause the paper web to tear off at the end of the formation of the logs.
Such devices, however, are not suitable for the present production requirements, as they are relatively unreliable or require frequent and costly service interventions.